1. Field
Aspects of embodiments according to the present invention relate to a thin film transistor and, more particularly, to a high-voltage thin film transistor with an offset structure.
2. Description of the Related Art
A thin film transistor (TFT) is a special type of a field effect transistor (FET) in which a thin semiconductor film is formed on an insulating supporting substrate. Similar to the FET, the TFT has three terminals, i.e., a gate, a drain, and a source, and performs switching as a main function. By adjusting a voltage that is applied to the gate, the TFT performs switching so that current flowing between the source and the drain may be in an “on” or “off” state.
A conventional high-voltage TFT is a type of TFT to which a high voltage is applied. The conventional high-voltage TFT may employ an offset structure so that it can be more resistant to the high voltage. A conventional offset structure has an offset region, which is a high-resistance region between a source region and a drain region. In general, if a high voltage is applied between the source region and the drain region, then the high voltage is also delivered to the high-resistance offset region, thereby preventing a high electric field from being formed on a channel layer. Accordingly, the TFT may be maintained at a sufficiently low level of “off” current Ioff.
However, since the high-resistance offset region is intentionally employed in the conventional high-voltage TFT in order to reduce bias stress caused when a high voltage is applied, the amount of “on” current Ion may eventually decrease.